Method for producing hydrocyanic acid



Patented Mar. 11, 1924.

UNITED STATES 1,485,592 PATENT OFFICE.

OTTO LIEBKNECHT, OF FRANKFORT-ON-THE-MAIN, GERMANY, ASSIGNOR TO THE ROESSLER & HASSLAGHER CHEMICAL COMPANY. OF NEW YORK, N. m- A CORPORA- TION OF NEW YORK.

METHOD FOR PRODUCING HYDROCYANIC ACID.

No Drawing.

To all whom it may concern:

-Be it known that I, Orro LinBKNncn'r, a citizen of the Republic of Germany, and resident of Frankfort'on-the-Main, Germany, haveinvented a-certain new and useful Method for Producing Hydrocyanic Acid, of which the following is a specification.

This invention relates to the manufacture of hydrocyanic acid and has for its object to produce a more etlicient method of making this acid.

Hydrocyanic acid has been made heretofore by the treatment of a cyanide solution with acids or acid salts and the application of external heat. Such processes are ineflicient in requiring the addition of external heat and are inconvenient in the handling of acids. The present invention overcomes 0 these disadvantages. If certain anhydrous salts of metals, whose bases form an unstable cyanide, are treated with a suitable cyanide iu the presence of water, the hydration heat of said metalsalts is 'suiiicient to driveoti' the ae hydrocya nic acid. It' has been discovered that the evolution .of hydrocyanic acid is favorably promoted if such quantities of suitable salts'for example, magnesium sulphate are added to the cyanide that the water remaining after the reaction iscomplete 'or nearly complete exists as watenof crystallization so that after the reaction products havc cooled, a more or less dry salt mixture remains.

In many cases it has been found advisable to add in addition to the materials specified above, additional salts, inactive as regards the desircdreaction involvingevolution of hydrocyanic acid and anhydrous or low in water 40 content and which form compounds containing water of crystallization such as for, example anhydrous sodium sulphate'or calcium chloride.

Th'c'heat of hydration of these salts which are added for the purpose of binding water can, of course, be utilized in accordance with the discovery disclosed in my prior application, Serial No. 496,046.

' As an example of the application of my invent-ion, one part by weight of sodium cyanide may bedissolvcd in 3.3 parts of water. 3.5 to 4.0 parts of anhydrous kieserite (magnesium sulphate) is then added to the solution. After a. short time a violent Application filed November 21, 1922. Serial No. 603,922.

form u nstable cyanides, with water, suchquantities of metallic salts being tlrt'aatcd-thatv substantially all the water remaining when the reaction is over exists as water ofcrystalllzation.

2. l'n'the process of making hydrocyanicjo acid from an alkali metal cyanide and metallic salts whose bases form unstabl% cyanidcs by treating them with water, the. improvement which com rises adding auxiliary salts which supply eat to the reaction but do not retard the evolution of hydrocyanic acid in such a quantity that substan- "tially all the water remaining when the reaction is over is found as water of crystallization.

3. The process of making h drocyanic acid winch comprises treating wit water an- I alkali metal cyanide and magnesium; sulphate in such quantity that substantially all of the water remaining when the reaction is over is found as water of crystallization.

4. The process of making 11 drocyanic acid which comprises treating wit Water an alkali metal cyanide, magneslum sulphate,

and calcium chloride, the quantity of magnesium sulphate being such that only water of crystallization remains when the reaction is over.

5. The process of making hydrocyenic acid which comprises treatm magnesium sulphate with a solution of so ium cyanide containing sulhcient water for the"heat of hydration of the magnesium sulphate to drive oil the hydroc anic acid formed, said magesium sulphate cin added in a quantity sutlicient to have all the water remaining when the reaction is finished, exist aswatcr of crystallization.

6. The process of making hydrocyanic acid which comprises treating magnesium sulphate, and calcium chloride, with a sol tion of sodium cyanide containing enou 11 water for the heat of hydration of the sa t8 to drive ofi hydrocyanio acid f0rmed,'the stantially dry residueremains when the re-,

quantity of magnesium sulphate being sufaction is over. ficient to retain all the water existing when In testimony whereof I have signed my the reaction is over as water of crystallizaname to this specification in the presence 5 tion n f k h d of two subscribing witnesses.

- 1e process 0 ma ing y roeyamc acid which comprises treating with water an OTTO .LIEBKNECHT' alkali metal cyanide, magnesium sulphate, and calcium chloride, the quantity of mage- 10 sium sulphate being such that only a sub Witnesses:

C. C. L. B. Wms, BASIL E. SAVARD. 

